Inspection camera

ABSTRACT

A camera constructed to photograph the interior of aircraft engine cylinders through spark plug holes which includes a lightsealed housing angled to focus the interior cylinder image. The camera includes a flash reflector tunnel which illuminates the specific area being photographed.

United States Patent i 1191 3,244,085 5/1966 Pulfcr Reinhold 95/1 1 HC J6 fa 1 3,759,i5i Metz [4 Sept. H8, 1973 INSPECTION CAMERA 1,470,708 10/1923 Blum 95/31 [76] Inventor: Raymdnd W. Metz, PO. Box 271, OR GN NTS 0R A PLI T O S v o Ca 91760 67,017 11/1943 Norway ass 241 22 Fl (1: S t. 21 1971 1 1e ep Primary Examiner-John M. Horan PP 1821374 Attorney-Ronald L. Juniper 52 us. c1. 95/11, 356/241 [571 ABSTRACT [51] Int. Cl. G03b 37/00, 00in 21/16 A camera constructed to ph t gr ph h interior of air- [58] Field of Search 95/ l 1; 356/241 craft engine cylinders through spark plug holes which includes a light-sealed housing angled to focus the inte- [56] References Cited rior cylinder image. The camera includes a flash reflec- UNITED STATES PATENTS tor tunnel which illuminates the specific area being 1,658,537 2/1928' Phmogmphed' 3 Claims, 5 Drawing Figures I/vvE/vroe BIN/MONO W M572 PATENTED SEP 1 8 I973 sum 2 0F 2 l/vvE/vrog Jens MONO W ME rz INSPECTION CAMERA I BACKGROUND OF THE INVENTION Broken piston rings in aircraft engines often go undetected until substantial damageto the cylinder walls has taken place. It is then necessary to replace the entire cylinder, making repairs more costly than it would have been had the problem been detected early enough. The problem is acute in newly re-man'ufactured engines. There, compression would not yet be up to normal during the breakinperiod. A broken ring'due to faulty installtion could go undetected for perhaps 100 hours of operation, during which time a cylinder would become severlyscored. v i a At the present time the condition of rings and'cylinders can be indirectly tested by measuring compression or the ability of the cylinder to retain a given amount of air pressure. If the cylinder is not air tight to the prescribed amount, the trouble is not pinpointed to ring failure. It could be oneof the following problems:

I. Faulty valve seating a ,2. Cracked piston 3. Broekn rings 4. Worn rings i g j I .A second method'ofinspection available at'present is to make a visual-inspection by utilizingan optical device called abore scope. Thisdevice allows an operator to visually scan the cylinder walls through a limited fieldof view. The disadvantage of this device, in the case where there is doubt as to the cause of the scratch, is'that one man views a potential scratch due to ring failure and makes a judgement to disassemble the cylin- V der or to watch it for awhile for a worsening of the condition. In viewing the scratch a second time at a later date,it may be difficult to determine the amount of deterioration since the previous inspection hasto berernembered. v

Therefore, to overcome these problems, it is a primary object of this invention toprovide a special camera to permanently record the condition of the cylinder walls after periods of operation. A piston ring failure then could be detected when it does no more damage than produce a fine scratch in the wall. Repair would then amount to no more than the relatively minor operation of replacing rings andnot the entire cylinder.

A further object of this invention is to provide a camera especially constructed to. photograph accurately the interior surface of aircraft engine cylinder walls which incorporates a light source sufficient to give correct exposure and a lens to provide a specific field of view. i

Thus an inspection camerawithin the purview of this invention to overcome these disadvantages of the prior art includes a lens carrying structure constructed to matingly fit through the cylindrical intercon of a spark I plug hole. A photographic chamber. within which the lens is mounted includesthefilm in aplane upon which the lens can focus. Insome forms the field of view desired requires angling the chamber and positioning a mii ror therein to reflect the object image in the plane of-the film. In order toproperly light, the cylinder interior flash units are carried on the sides of the camera chamber which direct their light through enclosed reflective flash tunnels so that the light is emitted through a diffuser ring surrounding the lens. The light is thereby directed exactly on the objects the lens is focused on, and in the case of cylinder interiors, covers a field of 2 view andarea virtually impossible to photograph with conventional cameras.

DESCRIPTION OF TI-IE DRAWINGS FIG. 4 is a cross-sectional end view taken through 4 4 in FIG. 3 showing the lens end of the camera.

FIG. 5 is a fragmented, longitudinally sectioned view taken through 5 5 in FIG. 3 showing the insertion of the camera lens through a spark plug hole.

DESCRIPTION 09 THE INVENTION aircraft engine 18 by placing the camera so as to re-,

ceive images through the spark ,plug holes 20 and 22. The same camera, designated l2,'can be used here by moving it from one spark plug hole to the other so as to encompass the desired field of view within an engine cylinder.

An embodiment of a camera in accordance with this invention includes a funnel-shaped Y photographic. chamber 30 enclosing at its larger end 32 a photographic film 34 held in a plane on which images received through the lens 36, carried within the cylindrical small end 38 of the chamber 30, can be focused. Because of the particular shape of the interior surfaces 14 of an aircraft engine cylinder and the relative location of the spark plug holes 20 and 22 through which the end 38 is inserted, the image pathway 40 is folded within the chamber 30 to photograph the desired field of view.

This folding of the image pathway 40 is achieved through bending the center of the chamber 30 by angling its housing 42 and placing a mirror 44along the angled sidewall so positioned that the image pathway 40 received through lens 36 is reflected at the precise orientation point 46 which will focus it on film 34 as shown in FIG. 2.

A type of film 34 which has been found suitable for use in this invention is Polaroid type black and white which has a very fast A.S.A. rating. This film 34 then can be inserted in the larger end 32 of the camera as part of a Polaroid film pack.

Since the interior of the engine cylinders within which photographs are intended to be taken with this camera are ordinarily quite dark, supplementary sources of light are usually required. However, in order to accurately photograph cylinder interiors the ordinary light sources 'cannot be placed to provide the de sired even lighting, in the same field of view, as that taken by the lens of this camera. Thus, special lighting tunnels 50 and 52 are positioned along the outside of chamber 30, as shown in FIG. 3, to emit light at their common termination in end 38 through a translucent diffuser ring 54 which surrounds a circular piece of glass 55 forward of the lens 36. t

The light sources 56 and 58 for these reflector tunnels 50 and 52, respectively, can be conventional electronic flash units such as Bauer Model Number I60 Ultrablitz units placed so that emitted light is directed down the tunnels toward light diffuser ring 54. In order to maximize the efficiency of the emitted light, the tunnel walls are preferably lined with reflective material. To provide as nearly even lighting as possible, the tunnels 50 and 52 on two opposite sides of chamber 30, join near end 38 to form a common tunnel portion 56 surrounding lens 36.

The lens 36 is preferably structured to provide a 45 field of view on all sides of the central axis of the image pathway 40 as shown in FIG. 5. An example of a lens which can be used for this purpose is comprised of three elements having the following characteristics wherein the Element I is nearest the object, Element II is intermediate, and Element III is nearest the film.

E. C. I. CAMERA OBJECTIVE Element Radius Thick- Glass Clear ness Aperture I Infinity 0.05 5 [7642 0.29 Infinity 0.045 0.22 ll 0.500 0.025- 1 648339 0.16 0.2258 0.1075 0.12 III I.783 0.573 734517 0.05 (Stop I Diameter) 0.434 0.29

A normally closed spring-loaded shutter 60 is hingedly mounted ona pivot pin 62 attached to an interior side wall of housing 42 adjacent to a fixed aperture iris 64 mounted transversely within the chamber 30 near its smaller end 38. The shutter 60 is opened by pulling a trigger 66, slidably mounted for longitudinal movement within a slot 68 in the side of housing 42 near the larger end 32, which, in turn, pulls the connected lever 70 to open the interconnected edge 72 of shutter 60. When so actuated, the trigger 66 and shutter 60 are moved to the dotted line positions shown in FIG. 2. 1

At the same time as the trigger 66 is pulled to open the shutter 60, an electrical circuit (not shown) is closed to simultaneously actuate the electronic flash units thereby providing the required amount of light to produce an image on the film 34.

axis of the image pathway. t

Though a single form of this invention has been described here, this is for illustrative purposes only so as to show the advantages of this invention. Specific variations suggested by this description of the invention are intended to be comprehended by it as within the spirit of the development as defined by the scope of the following claims.

I claim:

1. An inspection camera including: a funnel-shaped, light-sealed, photographic chamber having an open small end with an exterior cylindrical shape adapted to be matingly fitted on an engine spark plug hole, and a large end; photographic film carried in a plane in said chamber large end on which images received through said lens means can be focused; said photographic chamber being angled between its small end and its large end so that the axis of the image pathway received through said lens means strikes an interior side wall and a mirror is mounted on said interior side wall positioned to reflect images received through said lens means onto the plane of the photographic film; a translucent diffuser ring surrounding said lens means adjacent to the open small end of said chamber; at least one enclosed light reflector tunnel connected with said diffuser ring; photographic lighting means mounted within said light reflector tunnel positioned to provide illumination through said diffusor ring which is directed to flare out substantially evenly around the axis of the image pathway through the lens means toward the object area being photographed; a shutter means within said photographic chamber normally blocking light entering said open small end; trigger means for selectively opening said shutter for predetermined amounts of time; and electrical circuits means connecting said trigger means and said photographic lighting means to synchronize the shutter and the lighting means.

2. An inspection camera as defined in claim I wherein there are two reflector tunnels which are mounted on opposite sides of the photographic chamber and interconnected to said diffuser ring by means of a common tunnel portion.

3. An inspection camera as defined in claim 2 wherein the lens means is adapted to provide an approximately 45 field of view on all sides of the central 

1. An inspection camera including: a funnel-shaped, lightsealed, photographic chamber having an open small end with an exterior cylindrical shape adapted to be matingly fitted on an engine spark plug hole, and a large end; photographic film carried in a plane in said chamber large end on which images received through said lens means can be focused; said photographic chamber being angled between its small end and its large end so that the axis of the image pathway received through said lens means strikes an interior side wall and a mirror is mounted on said interior side wall positioned to reflect images received through said lens means onto the plane of the photographic film; a translucent diffuser ring surrounding said lens means adjacent to the open small end of said chamber; at least one enclosed light reflector tunnel connected with said diffuser ring; photographic lighting means mounted within said light reflector tunnel positioned to provide illumination through said diffusor ring which is directed to flare out substantially evenly around the axis of the image pathway through the lens means toward the object area being photographed; a shutter means within said photographic chamber normally blocking light entering said open small end; trigger means for selectively opening said shutter for predetermined amounts of time; and electrical circuits means connecting said trigger means and said photographic lighting means to synchronize the shutter and the lighting means.
 2. An inspection camera as defined in claim 1 wherein there are two reflector tunnels which are mounted on opposite sides of the photographic chamber and interconnected to said diffuser ring by means of a common tunnel portion.
 3. An inspection camera as defined in claim 2 wherein the lens means is adapted to provide an approximately 45* field of view on all sides of the central axis of the image pathway. 